This invention relates to apparatus and method for receiving a slab of wood sawn from a log and in one continuous operation producing boards having four substantially smooth surfaced sides.
Sawmill operations, as commonly practiced, have substantial inefficiencies in the apparatus and method in which they produce smooth- surfaced lumber. Although various apparatus and methods have been attempted in the past, the usual prior method is as follows.
A log initially is sawn lengthwise into a plurality of slabs having a variety of thicknesses. These thicknesses are determined by the contour and size of the log to obtain maximum yield from the log. These slabs are sawn to thicknesses somewhat in excess of that which is necessary for boards of standard thicknesses so that they can be planed to a desired standard thickness.
After the slabs are sawn from the log in a variety of thicknesses they then generally are separated into stacks according to thickness. A stack of slabs of all one thickness then is taken to gang saw apparatus which saws the slabs into individual boards of selected width.
Since the boards sawn from a slab may be of different widths, although they are all the same thickness, these then must be sorted as to width and stacked in their appropriate size ranges to provide separate stacks wherein each stack will include only boards of common width and thickness.
Then, each individual stack of boards which has a common thickness and width is taken to a combination planer/edger machine where the boards are fed individually therethrough to produce planed upper and lower surfaces and planed, or edged, side surfaces. Such planer/edger machines generally have had to be manually preset for each individual stack of boards having a specific thickness and width. The boards of all one thickness and width had to be fed through the planer/edger. Then when another stack with a different width-thickness configuration arrived the planer/edger had to be reset. It will be recognized that this is a time-consuming operation requiring a number of stacking, moving, sorting and equipment resetting steps.
Others have attempted to improve the efficiency of such operation by development of various apparatus, but such appears to have been unsuccessful, because the industry continues to operate generally as set out above, with the multiple cutting, sorting, stacking, and planing steps.
An object of the present invention is to overcome such inefficiencies of prior operations and produce apparatus and a method that are operable to receive slabs of various thicknesses and widths, and in one continuous series of steps, without intermediate sorting and stacking, produce a plurality of boards with all four sides smooth surfaced.
A further object of the present invention is to provide novel apparatus which senses the thickness of a slab sawn from a log introduced to a conveyor path extending through the apparatus, automatically sets a preferred vertical distance between upper and lower planing heads to remove material from the upper and lower surfaces of the slab as it is carried therethrough to produce a slab having smooth upper and lower surfaces with a thickness of a common size of boards to be produced from this slab, and downstream from the planing head has a series of upright laterally spaced saws operable to produce smooth cuts in the slab to produce boards having substantially smooth surfaces on all four sides.
Yet another object of the present invention is to provide such apparatus which includes hold-down mechanism adjacent the planing heads for controlling the positioning of a slab as it is moved along the conveyor through the planer head to produce accurate planing of the upper and lower surfaces.
Another object of the present invention is to provide a novel method for separating a slab sawn from a log into a plurality of boards having smooth surfaced sides which does not require multiple sorting, stacking and movement steps between various stages in the operation.
A further object of the invention is to provide on a common frame apparatus for sensing the thickness of a slab sawn from a log, varying the vertical distance between a pair of upper and lower planer heads to remove material from the upper and lower surfaces of the slab as it is carried along a path therebetween to produce smooth upper and lower surfaces, and a plurality of substantially upright saws spaced laterally at selected distances from each other downstream from the planer heads to saw the slab into boards of selected width having substantially smooth sides.
More specifically, an object of the invention is to provide a novel method for separating a slab sawn from a log into a plurality of boards having smooth surfaced sides, including the steps of moving a slab substantially horizontally along a path, sensing the thickness of the slab, providing upper and lower planing heads adjacent the top and bottom of the path, the lower head being preset to remove a minor portion of the underside of the slab to provide a finished surface thereon and the upper head being shiftable vertically relative to the lower head, positioning the upper head a selected vertical distance from the lower head in relation to the sensed thickness of the slab, moving the slab through the space between the planer heads to plane the slab to a selected thickness with smooth upper and lower surfaces, providing multiple upright saws in the path of the slab downstream from the planer heads spaced apart laterally desired distances for producing boards of select widths, and moving the slab through the saws to produce boards with smooth sides.
These and other objects and advantages will become more fully apparent as the following description is read in conjunction with the following drawings.